Dynamic voltage sharing device of multi-break vacuum circuit breaker and parameter selection method for dynamic voltage sharing device

Abstract

The invention provides a dynamic voltage sharing device of a multi-break vacuum circuit breaker and a parameter selection method for the dynamic voltage sharing device. A voltage sharing capacitor, a current limiting resistor and a zinc oxide arrester are used as a dynamic voltage sharing component of a multi-break serial vacuum circuit breaker; and the voltage sharing capacitor is connected in series with the current limiting resistor and then is connected in parallel with the zinc oxide arrester. The optimal value of relative parameters is selected in combination with vacuum arc model-based electromagnetic transient simulation according to a synthesis test. According to the technical scheme, reliable switch-off of a plurality of vacuum arc extinguish chambers during serial operation can be ensured, and the vacuum circuit breaker can be applied in the voltage range of 110kV and more than 110kV.

Description

technical field [0001] The invention belongs to the technical field of multi-fracture vacuum circuit breakers, and in particular relates to a dynamic pressure equalizing device and a parameter selection method for multi-fracture vacuum circuit breakers. Background technique [0002] Circuit breakers are important control and protection equipment in power systems, vacuum and SF 6 It is two kinds of excellent insulation and arc extinguishing medium widely used in circuit breakers. Vacuum circuit breakers have the advantages of less maintenance, suitable for frequent operation, no risk of explosion, no problem of liquefaction of low-temperature gas, and environmental friendliness. At present, they are widely used in the voltage level of 40.5 kV and below in my country's power system. SF 6 The gas has excellent thermochemical properties and strong electronegative properties, and its insulation and arc extinguishing properties are more suitable for the requirements of high volt...

AI Technical Summary

Problems solved by technology

Due to the saturation characteristics of the dielectric strength of the vacuum gap, the development of high-voltage single-break vacuum circuit breakers is relatively slow

In the 1990s, a single-break vacuum circuit breaker with a rated voltage of 140 kV and a breaking current of 40 kA was reported abroad; in June 2010, the ZW□-126 / T2000-40 type was trial-produced and developed by Xi’an Xidian High Voltage Switchgear Co., Ltd. The outdoor high-voltage vacuum circuit breaker has passed the type test, but there is no engineering application at present

However, due to the significant difference in arc characteristics and after-arc dielectric strength recovery characteristics between vacuum circuit breakers and SF6 circuit breakers, the existing experience in the application of voltage equalizing capacitors cannot be directly applied to multi-fracture vacuum circuit breakers.

Some research results show that the breaking capacity of the double-break vacuum circuit breaker does not increase monotonously with the increase of the voltage equalizing capacitance; Negative impact on the breaking capacity of double break vacuum circuit breakers

According to the analysis, for a multi-fracture vacuum circuit breaker, when a fracture occurs, the voltage equalizing capacitor connected in parallel will discharge it, forming a transient discharge current, that is, the reignition current, and the existence of the voltage equalizing capacitor will increase If the transient current amplitude and decay time are large, the time for the unreignited fracture to bear the total transient recovery voltage becomes longer, which reduces the breaking capacity of the multi-break vacuum circuit breaker

In addition, when the dynamic and static contacts of each fracture are not separated at the same current zero-crossing point due to asynchrony, or when there is reignition at the fracture, the disconnected fracture before zero-crossing or the unreignited fracture will bear the total transient recovery voltage, which may lead to re-ignition ; After zero crossing, the separation fracture or re-ignition fracture will face too high power frequency recovery voltage, which may pose a threat to the insulation outside the fracture. Therefore, it is necessary to take relevant measures

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